In recent years, a wiring pattern of a substrate is formed by an inkjet technology. A wiring pattern can be directly formed on a substrate by the inkjet technology, so that high-cost processes, such as vacuum deposition, photolithography, etching, and resist removing process, can be omitted. As a result, a substrate can be produced at low costs.
Incidentally, when a wiring pattern is formed by using an inkjet head, fluid ink (droplets) containing a wiring material is jetted out and landed on a predetermined position on a substrate. When the droplets are discharged and landed on a substrate as above, there is a possibility that the droplets spread too much or come off due to the characteristics of a surface of the substrate. Therefore, there is a problem that a desired wiring pattern cannot be obtained.
In view of this, Japanese publication for Unexamined Patent Application Tokukaihei, No. 11-204529, (published on Jul. 30, 1999) discloses a method by which a desired wiring pattern can be formed while suppressing spreading or coming off of landed droplets as much as possible.
In the technology disclosed in the above publication, a surface of a substrate is modified beforehand so that an area, in which a wiring pattern may be provided, has affinity with droplets and the other area does not have the affinity. Then, the wiring pattern is formed by discharging droplets onto the affinity-having area (pattern forming area) on a substrate. In this case, the area except for the pattern forming area does not have affinity with droplets. Therefore, the droplets, which land on the pattern forming areas on a substrate, do not spread beyond the pattern forming areas.
Further, in the technology disclosed in the above publication, the droplets are discharged to be overlapped partially with each other on the pattern forming areas so that the landed droplets do not come off from the substrate. This prevents landed droplets from coming off.
However, in the pattern forming method disclosed in the above publication, the number of discharged droplets is large, because the wiring pattern is formed by discharging the droplets so that the droplets overlap partially with each other to prevent the landed droplets on a substrate from coming off. In such a case, there are problems that (i) a processing time (tact time) for a series of steps until forming the wiring patterns will increase due to an increase of the number of the droplets to discharge, and (ii) an operating life of an inkjet head will be shortened.
The present invention was made to solve the above problems, and an object of the present invention is to provide a pattern formation substrate and pattern forming method which attains a satisfactory wiring characteristics, while preventing an increase of a tact time and an operating life shortening of an inkjet head by decreasing the number of discharged droplets.